The participation of small mammals (SM) in the migration of essential (Cu, Zn) and toxic (Cd, Pb) trace elements (TEs) in forest ecosystems under conditions of severe industrial pollution of the environment (1990–2000) by a large copper smelter (Middle Urals, Russia) and after a significant reduction in its emissions (2010–2019) was considered. The peculiarity of transit food flows (TFF) in the pollution gradient was determined by the composition and abundance of animals of different trophic groups (phytophages, mixophages, zoophages), as well as the specifics of their diet. The reduction in emissions was accompanied by positive changes in the SM communities, expressed in an increase in the number and structural rearrangements of trophic groups (TG), which led to partial changes in the composition and amount of food consumed, as well as the content of TEs in them. By the end of the observation period in the background zone, the animal-controlled TFF remained stable for most TEs (Cu, Zn, Cd), for Pb it decreased by a factor of 2, but not as a result of reduced emissions. In contaminated areas, the value of TFF Zn has not changed, Cd has increased, Cu and Pb - decreased. It was concluded that in the taiga zone the main contribution to the dynamics of biogenic TEs flows over time and space was made by a group of mixophages that dominated the pollution gradient.

The accumulation of 28 elements (Na, Ca, Sc, Cr, Fe, Co, Zn, As, Br, Rb, Sr, Ag, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Au, Th, U) in a maternal organism (the liver), the placenta and fetuses of the bank vole (Clethrionomys glareolus) from the vicinity of a large copper smelter and from the background territories (Russia, the Middle Urals) has been analyzed. It was shown that the level of trace element contamination (TEC) of the environment had no significant effect on the levels of elements in different types of samples. The exception was Br: its concentrations in the liver, placenta and fetuses from contaminated territories exceeded twofold the respective background values. At the same time, the type of accumulation of most elements depended on the sample type: the maximum concentrations of Cr, Fe, Zn, Rb, Sb, La, Ce accumulated in the liver of maternal individuals; Co, Ag, Eu, Tb, Th accumulated in the placenta; Na, Ca, Br, Ba, Ta accumulated in fetuses, and the levels of As, Cs, Nd, Lu, U did not vary between the samples compared. It was concluded that the TEC components under consideration in effective concentrations had no significant negative impact on the bank vole offspring quality in the area of the copper smelter.

The temporal dynamics of species diversity and projective coverage of herbaceous communities formed on fallows and dumps was studied. Annual studies of these phytocoenotic indicators were carried out in four groups on the territory of the Tagil zone of the Middle Urals in 2006–2019. The successional development of communities depends on edaphic factors. Phytocenoses with a projective coverage and species diversity typical for meadow communities on the background territories develop on agrozems and technozems under conditions of low soil contamination with heavy metals. The meadow stage under conditions of high pollution is short, and it is characterized by low values of the studied parameters. Other trajectories of succession: a long delay in the grass stage or skipping the meadow stage and transition from grass to tree-shrub stage, are also possible. The species diversity of communities is more conservative compared with the total projective coverage of species, the rate of development of which is largely determined by the successional age of the community than by the type of substrate.

Abstract—The features of the restoration of the diversity of plant communities formed under different edaphic conditions were studied. In the period of 2006–2020, restorative successions on the territory of the Tagil zone of the Middle Urals were observed on nine sites, five of which were fallow lands, and four were overgrown anthropogenic pits. In the course of direct observations of the communities of fallow lands and pits, four groups of phytocenoses were identified, reflecting successive stages of succession: gramineous phytocenoses with maintaining their status during the study period; gramineous phytocenoses with subsequent transition to the meadow stage; and early meadow and formed meadow phytocenoses. The temporal dynamics of their species composition and alpha diversity was studied. Differences in indicators of diversity of communities associated with their successional age and physicochemical parameters of soils (agrozems and technozems) were established. Communities of agrozems and technozems differed in the rate of change in alpha diversity indicators. The increase in these indicators occurred significantly faster on agrozems than on technozems. The transition between stages was not accompanied by a significant increase in the diversity of communities on technozems.

The fertility and viability of pollen grains of two morphological forms of Taraxacum officinale Wigg. s.l. were estimated. These forms compose common coenopopulations growing in various coenotic and edaphic conditions. The forms studied possess developed gynoecia-a large number of fertile pollen grains capable of germinating under certain temperature conditions. This fact points to the amphimictic properties of the plants. Comparison of the data on the fraction of fertile pollen grains and seed productivity allows assuming that some seeds develop without fertilization. This can be considered as evidence of the apomictic properties of plants. Therefore, the presence of facultative apomixis in the species considered was confirmed indirectly in our work. The fertility of pollen grains was shown to be a characteristic of the male gametophyte that was more environmentally dependent than its viability. Under favorable conditions, the share of fertile pollen grains in f. dahlstedtii and f. pectinatiforme differ insignificantly. Under stress, the differences between the dandelion forms by this index increase. This can be considered as a mechanism of adaptation to adverse environmental factors. The revealed differentiation of the morphological forms of dandelions by the index of pollen grain fertility suggests that edaphic and coenotic stresses increase the differences between them in the degree of apomictic and amphimictic properties. The morphological forms of dandelions, by realizing two reproductive strategies under stress, ensure both the abundance and the genetic heterogeneity of the coenopopulations. The morphological forms studied do not differ in the proportion of viable pollen grains. This index increases in the gradient of coenotic competition only to a certain extent, which can be considered as a manifestation of the properties of the facultative apomict.

The paper addresses the removal of chemical elements by suprasoil and subsoil phytomasses of herbaceous phytocenoses and their subsequent return to soil during decomposition of plant remnants. The obtained results allowed us to evaluate the biogeochemical cycles of essential (Zn, Cu) and toxic (Pb, Cd) elements in natural biogeocenoses of the Middle Urals. It has been shown that the intensity of such an exchange in areas subjected to variable anthropogenic impact is determined not only by the direct influence of mobile forms of chemical elements, which are contained in soils and operate as environmental pollutants, but also by a combination of edaphic (physicochemical parameters of soils), coenotic (abundance and correlation of agrobotanical groups in phytocenosis) and microbiological (level of evolution of soil microbiocenosis) conditions.

The paper presents data on the involvement of local populations of bank vole ( Clethrionomys glareolus ) in the biogeochemical cycles of Cu, Zn, Cd, and Pb at territories strongly chemically polluted by large nonferrous metallurgical plant in the Middle Urals (in 1990–1992) and after a significant decrease in its emissions (in 2015–2017). At maximally polluted areas (impact zone), the animal-controlled transit Cu, Cd, and Pb flows approached their background values by the end of the study period, and the Zn flow simultaneously twofold decreased compared to the background areas. At moderately polluted areas (buffer zone), no significant changes in the metal fluxed were detected for any of the elements. The specifics of the transit flows of the elements at variably polluted areas are controlled by the concentrations of these elements in the diet of the animals and by the abundance of voles. Thereby the manyfold (fifty-fold) decrease in the emissions did no result in an equivalent decrease in the concentrations of the metals in the animal rations at the polluted areas. The main reason for the changes was a structural transformation in the community of the small mammals, which led to a drastic decrease in the bank vole population in the impact zone. The simultaneous effects of the analyzed factors over the study period of time (25 years) resulted in intensification (in the background zone), retardation (impact zone), and stabilization (buffer zone) of the biogeochemical exchange of the elements.

— Based on the analysis of dose–response relationships under exposure to a wide range of copper sulfate concentrations, the metal tolerance of seed progeny was assessed using the root elongation test in two morphological forms of Taraxacum officinale Wigg. s.l. growing in background and technogenically transformed areas (industrial waste dumps). Since previous studies in the same areas showed that these forms differed in their abundance and ratio in the coenopopulations and in the level of copper accumulation, it was assumed that they would also differ in the metal tolerance of seed progeny. It was found that the average values of effective copper sulfate concentrations inhibiting root growth in seedlings by 10, 50, and 90%, did not differ between the study areas and between the morphological forms of dandelion.

This paper is concerned with the phytomass of herbaceous phytocenoses growing in anthropogenically impacted areas in the Middle Urals at different stages of succession along the heavy-metal pollution gradient. Cenoses of young soils of dumps have less resistance and higher sensitivity to changes in weather factors, in contrast to the phytocenoses of the deposits. It is shown by general regression models that the epiterranean and subterranean biomass of cenoses on technozems depends on Selyaninov’s hydrothermic coefficient for September and the amount of precipitation in October–November of the previous year and in January–May of the current year. The degree of this dependence for cenoses under research is determined by edaphic conditions that affect the species diversity and dominance structure.

The structural and functional diversity of the main ecological trophic groups of soil microorganisms in meadow soils of the Central Urals anthropogenically contaminated with heavy metals was studied. The increase in the total numbers of these microorganisms in technozems, in comparison with those in agrozems, is due to the higher abundance of iron-reducing, denitrifying, nitrogen-fixing, and sulfate-reducing bacteria, an increase in cellulolytic activity, and the dependence of these characteristics on the toxic load of the soil. A reductive structure of the microbial community with the predominance of r-strategists, which reflects earlier stages of microbiocenoses succession under soil contamination, is formed under soil pollution with heavy metals.

Traditional approaches to structural analysis of biotic communities, based on the data on species abundances, do not take into account phylogenetic relationships between these species. We propose a new approach to studying the scaling (scale dependence) of phylogenetic diversity by means of multifractal analysis in which the moments of phylogenetic diversity are used. The results of applying this approach to small mammal communities of Nizhny Novgorod region of the Volga Basin has shown that phylogenetic diversity scaling complies with the power law, which is indicative of the self-similarity of these communities. The multifractal spectra of phylogenetic diversity scaling markedly differ from the spectra of species diversity scaling, providing evidence that the proposed approach can provide novel information on the structure of biotic communities.

An attempt was made to estimate the dimension of direct toxic effects of exposure to Cd on the basis of researches on reproductive parameters in small mammals in natural populations ( on the example of red-backed vole) inhabiting localities of large-scale non-ferrous metal plants and comparison of results obtained with outcome of toxicological experiments ( chronic exposure of female rats to Cd) ). It was expected that at the existing pollution levels, embryonic losses caused by direct toxic effect of Cd shouldn’t exceed 7%; however actual losses significantly exceeded extrapolation results. Distinctions observed are caused by impact of external and internal factors influencing reproductive potential on fulfillment of reproduction of animals in natural populations.

Consideration is given to production and decomposition processes in herbaceous communities exposed to chemical pollution with heavy metals in the Middle Urals. High variation in the aboveground phytomass of agrobotanical groups (legumes, forbs, grasses) is due to spatial heterogeneity of soil pollution levels and consequent changes in the species composition of plant communities in the areas studied. Therefore, nonparametric statistical methods have been used (Kruskal–Wallis test with subsequent pairwise comparisons by Wilcoxon–Mann–Whitney with Bonferroni correction for multiple comparisons). The phytomass of legumes remains unchanged in the increasing pollution gradient, while the contribution of forbs to the total phytomass decreases and that of grasses increases. Soils rich in nutrient elements can maintain a high rate of plant debris decomposition, counterbalancing the adverse effect of increased heavy metal concentrations on relevant processes. The balance between production and mineralization processes provides for the sustainable, long-term existence of herbaceous communities under conditions of intense pollution of the natural environment.

In this paper we consider the indicative role of chemical composition of the small mammal (specifically, the bank vole, or Myodes glareolus) reproductive system with the purpose of studying the impact of a large-scale nonferrous metal-processing enterprise on living organisms through the expample of Middle Ural copper-smelting plant OJSC. We have analysed the chemical composition of the placenta-embryo system in the areas which are 2 km and 30 km away from the plant.